Device for producing a hot propellant jet

ABSTRACT

There is disclosed a device for producing a hot propellant jet intended to atomize, and subsequently vitrify, liquid inorganic melts such as, for instance, slags or glass, including a burner chamber. The burner chamber has inlet openings for water and/or vapor distributedly arranged in the axial direction and about the periphery of the flame in a wall surrounding the burner axis and forming an annular chamber with the wall of the burner chamber. A lance including a nozzle is connected to the burner chamber.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a device for producing a hot propellantjet intended to atomize, and subsequently vitrify, liquid inorganicmelts such as, for instance, slags or glass, including a burner chamber.

[0003] 2. Prior Art

[0004] To granulate and disintegrate liquid slags, it has already beenproposed to eject the same into granulation spaces by the aid of vaporor a propellant gas, it having also been proposed to carry out furthercomminution in jet mills using a propellant jet. Departing from slagtemperatures of between 1400° C. and 1600° C., the use of conventionalpropellants, due to the relatively high temperature difference betweenthe propellant jet and the liquid slag, entails the risk of theformation of more or less large agglomerates as well as the danger ofthread formation, which, as a result, will raise comminution expensesand considerably reduce the cooling speed. The known proposals,therefore, primarily aimed to effect the cooling of liquid slags asrapidly as possible. According to another proposal, the liquid slag wasejected into a granulation space along with combustion offgases in orderto reduce the risk of obstruction of a slag outlet opening from a slagtundish by solidifying slag. By such a mode of procedure, the slagparticles injected into the granulation space will reach a consecutivelyarranged cooling zone at a substantially higher temperature, the highertemperatures resulting in a reduced slag viscosity and a reduced surfacetension of the slag droplets so as to enable a finer division of slagdroplets at the entry into the cooling zone. The fine dispersion of slagdroplets causes the formation of extremely small droplets withrelatively high specific surfaces, which allows cooling in relativelyshort-structured cooling chambers. In such a device in which combustionoffgases are used as propellants, vapor and/or water under pressure issubsequently directed against the slag jet within the cooling chamber inorder to ensure accordingly rapid cooling.

SUMMARY OF THE INVENTION

[0005] The invention now aims to provide a device for producing a hotpropellant jet, by which it is feasible in a simple and cost-effectivemanner to form a vapor and a vapor-gas mixture for such a propellantjet, in which the temperature of the propellant may be adjusted andcontrolled within wide limits. It is known that high propellanttemperatures result in an extremely fine atomization of the slagparticles, whereby the diameters of the slag droplets can be kept atbelow 15 μm. At lower temperatures such as, for instance, temperaturesranging between 600° C. and 1350° C., the maximum slag diameterattainable will change exponentially, maximum particle diameters of 110μm being observed, in particular, at propellant jet temperatures ofabout 600° C. as opposed to a maximum particle diameter of 15 μm to beobtained in a propellant jet of about 1350° C. If the temperatures ofthe propellant vapor or propellant gas jet are even lower, the initiallymentioned thread formation will occur. Such a thread formation may beintended, though, if, for instance, slag wool, glass fibers orinsulating wool are to be produced.

[0006] In order to provide a structurally simple device of the initiallydefined kind, which allows for a wide range of control of thetemperature of the propellant jet, the configuration according to theinvention essentially is characterized in that the burner chambercomprises inlet openings for water and/or vapor distributedly arrangedin the axial direction and about the periphery of the flame in a wallsurrounding the burner axis and forming an annular chamber with the wallof the burner chamber, and that a lance including a nozzle is connectedto the burner chamber. By providing an additional wall in the interiorof the burner chamber, it is feasible, on the one hand, to arrange theinlet openings for water and/or vapor, which are formed, for instance,by bores or slots, in a suitable manner to effect the nozzling of waterand/or vapor into the propellant jet and, in particular, into the flameof the burner, while, at the same time, an annular chamber is formed,which is accordingly cooler than the flame on account of the water underpressure or vapor supplied. As a result, the interior of the burnerchamber, in which the fuels are burned by means of a flame, may becooled by radiation cooling, whereby a major portion of the burnerchamber can, thus, be efficiently cooled and hence be formed of simplermaterials. An additional refractory lining or configuration with arefractory material such as, e.g., alumina, magnesite, silica,zirconium, quartz, silicon carbide or silicon nitride may be requiredmerely in the lower part of a burner chamber of this type in case thewater or vapor supply is adjusted such that relatively high propellantjet temperatures will result. By the controlled introduction of waterunder pressure or vapor into the annular chamber, the desiredtemperature may be adjusted within wide limits, the burner chambersystem corresponding to some type of an internally fired steamsuperheater. Thermodynamically, such a configuration yields an optimumefficiency of nearly 100%, whereby a short heat transition period may berealized by appropriate turbulences in the burner chamber such that arelatively small-structured and extremely compact cost-effective designwill do as compared to conventional superheater systems. The combustionenthalpy of the vapor burner chamber may be recovered to the majorextent at a lower temperature level in the subsequent cooling andvitrification chamber into which the liquid inorganic melts are ejected,thus ensuring a high energetic efficiency.

[0007] Advantageously, the device according to the invention is furtherdeveloped in a manner that the inlet openings for water and/or saturatedvapor are arranged in a substantially bell-shaped or conical wallprovided in the interior of the burner chamber. By such substantiallyconical or bell-shaped wall parts delimiting the externally arrangedannular chamber towards inside, the expansion of the vapor upon entryinto the flame space is taken into account, whereby the transfer of thecooling vapor into the burner space in a particularly simple manner maybe effected via a perforated or slotted sheet metal, conventionalmaterials such as, for instance, materials employed in the constructionof gas turbines being usable therefor. In a particularly advantageousmanner, the configuration is devised such that the bell-shaped orconical wall encompasses the burner of the burner chamber concentricallywith the generating lines of the wall being designed to diverge from theburner nozzle towards the flame tip of the burner.

[0008] In order to take into account the rapid expansion of the vaporafter the transition into the burner chamber, the configurationalternatively also may be devised such that the inlet openings for waterand/or saturated vapor are arranged in a substantially cylindrical wallconcentrically surrounding the axis of the burner, the clear widths ofthe openings differing from one another in different cross sectionalplanes and increasing, in particular, towards the tip of the flame. Thetemperature of the hot burner flame, which is about 2400° C. at anadiabatic combustion, may in any event be adjusted to the requiredtarget temperature of, for instance, between 120° C. and 1350° C. by theaddition of wet or saturated vapor, the burner chamber being directly orindirectly cooled by wet vapor or saturated vapor.

[0009] Suitable adjustment or control of the respectively desiredoperating parameters is feasible in that a relief valve controllable ina pressure-dependent manner is connected to the annular chamber, whichrelief valve is controllable by the supply pressure of the propellantjet. In this manner, the pressure prevailing within the annular chamber,which becomes active as an evaporator or superheater chamber, may becontrolled accordingly and relieved with a view to enabling, forinstance, the preheating of fuels by the aid of the thus loweredpressure so as to impart the respective supply pressure on the same.Advantageously, controlling also may be effected in a manner that thefeed of water, vapor, combustion air and/or fuels to the burner chamberis conducted via a control valve capable of being controlled as afunction of the pressure and/or temperature of the propellant jet. Inthis manner, it is feasible in any event to maintain a defined pregivensupply pressure in the burner lance connected thereto and adjust thedesired temperature according to demands.

[0010] The transition from the burner chamber into the consecutivelyarranged lance advantageously may be realized in a manner that theburner chamber is connected with the lance via a funnel, which offersfluidic advantages and provides the option to obtain the respectivepressure and temperature measurements required for controlling, in theregion of the funnel or at the funnel outlet.

[0011] The device according to the invention advantageously is used in amanner that liquid inorganic melts and, in particular, slags or glassare ejected through a nozzle into a consecutively arranged cooling orvitrification chamber, the lance having to be adjustable relative to thenozzle to eject the liquid inorganic melts. To this end, theconfiguration advantageously is devised such that the burner chamber ismounted so as to be adjustable in the height direction together with thelance. In order to safeguard the respective thermal resistance of thelance in the region of the hot slag, the configuration advantageously isdevised such that the lance is comprised of an oxide-dispersivesuperalloy, in particular Fe or Ni base material with Al, Cr and lessthan 1 wt.-% Y₂O₃. Y₂O₃ raises the high-temperature creep resistance,while admixtures of aluminum and chromium offer a protection against hotcorrosion and, in particular, oxidation in the region of the mouth ofthe lance.

[0012] The burner itself may be operated with hot air, for instance in atemperature range of between 800° C. and 1200° C., as well as naturalgas but also crude oil and carbon dust, whereby CO₂, H₂O and nitrogenoxides are formed in the burner chamber and a relatively high nitrogenportion remains, taking into account the hot air employed. When coolingwith saturated vapor at 2 bars within the burner chamber, cooling to900° C. will yield extremely superheated water vapor having a relativelyhigh nitrogen portion such that a largely inert propellant jet isformed. Such a mode of operation in subsequently provided physicalvitrification procedures offers the particular advantage that the N₂portion contained in the propellant jet substantially decreases the dewpoint and possible undesired condensation procedures in the coolingsystem are more readily avoided. Hot air may be produced in aconventional manner in regenerative heat exchangers.

[0013] For economic reasons, the atomization of liquid blast furnaceslags may preferably be effected by the aid of hot blast and, forinstance, natural gas, the respectively desired particle size beingadaptable to the respective requirements by adjusting the temperature ofthe propellant gas and accordingly adjusting the lance in the slag exitnozzle. Because of the option to adjust the vapor temperature withinwide limits, also different melt temperatures of the inorganic melts,which usually range between 1180° C. and 1560° C. in the case of oxidicslags, may be taken into account.

[0014] By the burner chamber according to the invention, it is, forinstance, feasible to produce, and use as a propellant jet, 1000 g vaporat a temperature of 1350° C. under a pressure of 2 bars, using 17 ghydrogen and 136 g oxygen as well as 848 g vapor at 2 bars and 145° C.Alternatively, 10 g hydrogen and 81 g oxygen may yield a target quantityof 1000 g vapor at a temperature of 800° C. and 2 bars, using 909 gvapor at 2 bars and 145° C., the vapor fed at 2 bars at first beingrelieved to the pressure of the burner chamber via the perforated wallsand subsequently being again superheated by the flame.

BRIEF DESCRIPTION OF THE DRAWING

[0015] The device according to the invention for producing a hotpropellant jet will now be explained in more detail by way of anexemplary embodiment schematically illustrated in the drawing, wherein:

[0016]FIG. 1 illustrates a burner chamber including a lance connected tothe burner chamber, and

[0017]FIG. 2 is a detailed view of the arrangement of the vapor lancewithin the slag outlet.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0018]FIG. 1 depicts a burner chamber 1 whose external wall is denotedby 2. The burner is supplied with O₂, air or hot air via a duct 3 andwith fuels such as, e.g., H₂, CH₄, CO, natural gas, crude oil or carbonvia a duct 4, in order to form a flame 5, which flame 5 is surrounded bya conical wall 6 comprising inlet openings 7 for water and/or vapor,which are distributedly provided about the periphery of the flame 5.Between the conical wall 6 and the external wall 2 of the burner chamber1 is thus formed an annular chamber 8 into which wet or saturated vaporor water is introduced through a connection means 9. The vapor or waterintroduced into the annular chamber 8 rapidly expands due to the heatradiated off the flame 5, whereby further superheating of the vapor upto 1350° C. is attained in that the vapor is ejected from the annularchamber 8 into the immediate region of the flame 5 through the openings7. In doing so, the flame 5 is cooled from a temperature ofapproximately 2400° C. to the required target temperature of between120° C. and 1350° C.

[0019] The burner chamber via a funnel-shaped lower part 10 lined with arefractory material is connected with the vapor lance 11 which openswithin a slag jacket 13 emerging through a slag nozzle 12. A pressuremeasuring means 14 as well as a temperature measuring means 15 areprovided to control and adjust the parameters of the vapor jet. To thisend, a relief valve 17 to be controlled in a pressure-dependent manneris triggered via a control line 16 to relieve the annular chamber 8, thesupply of O₂, air, hot air and combustible to the burner beingcontrolled via a control line 18 and valves 19 installed in ducts 3 and4 as a function of the pressure and temperature values.

[0020]FIG. 2 is an enlarged view of the arrangement of the vapor lance11 within the slag nozzle 12 and the slag jet 13 ejected in the form ofa hollow cylinder. It is apparent that the end of the vapor lance 11 isconfigured as a nozzle 20 so as to ensure the optimum atomization of themelt. The acceleration due to gravity causes the gradual diminution ofthe wall thickness of the hollow slag cylinder 13 until the latterstarts to divide itself into individual skeins in region 21. It hasproved to be advantageous if the mouth of the nozzle 20 is approached toclosely before of the region of skein formation. This will be extremelybeneficial to the slag atomizing procedure. Another decisive parameteraimed at an efficiency increase is the length of the free jet, which hasa particular influence on the specific propellant consumption. Thelength of the free jet is defined as the length between the exit of thepropellant vapor from the lance nozzle 20 and the point of impact of thepropellant jet on the hollow melt cylinder 13. This length in theinstant case is to be kept as small as possible. The vapor lance 11 isarranged to be adjustable in the height direction in the sense of doublearrow 22 so as to enable the precise adjustment of the point of impactof the vapor jet on the hollow slag cylinder and the minimization of thelength of the free jet.

What I claim is:
 1. In a device for producing a hot propellant jetintended to atomize, and subsequently vitrify, liquid inorganic meltssuch as, for instance, slags or glass, of the type including a burnerchamber containing a burner having a burner axis and constructed toproduce a flame within said burner chamber and a burner chamber walldefining said burner chamber, the improvement comprising a further wallsurrounding said burner axis and forming an annular chamber with saidburner chamber wall, a plurality of water and/or vapor inlet openingsarranged in said further wall in a manner distributed in the directionof said burner axis and about the periphery of said flame, and a lanceincluding a lance nozzle and connected to said burner chamber.
 2. Adevice as set forth in claim 1 , wherein said vapor is saturated vaporand said further wall including said plurality of water and/or vaporinlet openings is a substantially bell-shaped wall arranged in theinterior of said burner chamber.
 3. A device as set forth in claim 1 ,wherein said vapor is saturated vapor and said further wall includingsaid plurality of water and/or vapor inlet openings is a substantiallyconical wall arranged in the interior of said burner chamber.
 4. Adevice as set forth in claim 2 , further comprising a burner nozzle andwherein said substantially bell-shaped wall encompasses said burner ofsaid burner chamber concentrically with the generating lines of saidsubstantially bell-shaped wall being designed to diverge from saidburner nozzle to the tip of said flame produced by said burner.
 5. Adevice as set forth in claim 3 , further comprising a burner nozzle andwherein said substantially conical wall encompasses said burnerconcentrically with the generating lines of said substantially conicalwall being designed to diverge from said burner nozzle to the tip ofsaid flame produced by said burner.
 6. A device as set forth in claim 1, wherein said vapor is saturated vapor and said further wall includingsaid plurality of water and/or vapor inlet openings is a substantiallycylindrical wall concentrically surrounding said burner axis, and saidwater and/or vapor inlet openings have clear widths respectivelydiffering from one another in different cross sectional planes.
 7. Adevice as set forth in claim 6 , wherein the clear widths of said waterand/or vapor inlet openings increase towards the tip of said flame.
 8. Adevice as set forth in claim 1 , further comprising a relief valveconnected to said annular chamber and capable of being controlled in apressure-dependent manner by the pressure of said hot propellant jet. 9.A device as set forth in claim 1 , wherein said burner chamber isprovided for the supply of at least one of water, vapor and combustionair, and further comprising a control valve capable of being controlledas a function of at least one of the pressure and the temperature ofsaid hot propellant jet, wherein said supply of said at least one ofwater, vapor and combustion air to said burner chamber is conducted viasaid control valve.
 10. A device as set forth in claim 1 , furthercomprising a funnel means constructed to connect said lance with saidburner chamber.
 11. A device as set forth in claim 1 , wherein saidburner chamber is mounted so as to be adjustable in height along withsaid lance.
 12. A device as set forth in claim 1 , wherein said lance iscomprised of an oxide-dispersive superalloy.
 13. A device as set forthin claim 12 , wherein said oxide-dispersive superalloy comprises a basematerial selected from the group consisting of Fe and Ni, admixed withAl, Cr and less than 1 wt.-% Y₂O₃.